South Korean (R) and US (L) Marines take part in a previous joint naval drill in April 2013. North Korea has put troops on alert again a joint naval drill taking place this week. Photo: AFP

North Korea warned the United States of “horrible disaster” on Tuesday as the isolated communist state put troops on alert against a joint naval drill involving a US aircraft carrier.

North Korean troops had been ordered to “keep themselves fully ready to promptly launch operations any time”, a spokesman for the General Staff of the Korean People’s Army said, in a statement carried by the state-run Korean Central News Agency.

The massive naval drill near the Korean peninsula is being staged by the United States, South Korea and Japan from Tuesday to Thursday and involves the nuclear-powered carrier USS George Washington.

It comes after Seoul and Washington last week signed a new joint strategy to counter the growing threat of a North Korean nuclear or chemical weapons attack.

The North Korean statement said the situation on the peninsula was “getting strained again” and warned the US that the closer its forces came “the more unpredictable disasters their actions will cause”.

“The US will be wholly accountable for the unexpected horrible disaster to be met by its imperialist aggression forces,” the statement said.

“The US should bear in mind that the Korean people and army are highly alert to promptly and confidently cope with and foil blatant provocations of any hostile forces in the world with its own powerful military muscle.”

North Korea has habitually condemned joint army drills staged south of the border and has issued threats of counter-attacks that have rarely materialised.

The North’s atomic test in February - its most powerful to date - triggered months of heightened military tension on the peninsula.

Pyongyang threatened pre-emptive nuclear strikes against Seoul and Washington, while the Pentagon has responded by deploying nuclear-capable B2 stealth bombers during past joint exercises with Seoul.

Tensions eased somewhat in recent months after the North changed tack to make a series of conciliatory gestures to Seoul, including an agreement to hold family reunions for those separated during the Korean War.

But acute concerns remain over the North’s nuclear programme, with a US think tank saying last week that Pyongyang has clearly restarted an ageing plutonium reactor.